Chem Exam - Phases of Matter

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kinetic molecular theory of matter

the idea that particles of matter are always in motion

Ideal Gas

an imaginary gas that perfectly fits all the assumptions of the kinetic-molecular theory

The 5 Assumptions of an Ideal Gas

1) Gases consist of large numbers of tiny particles that are far apart relative to their size2) Collisions between gas particles and between particles and container walls are elastic energy3) Particles are in continuous, rapid, random motion.4) There are no forces of attraction or repulsion between gas particles5) The average kinetic energy of gas particles depends on the temperature of the gas

Diffusion

spontaneous mixing caused by the random motion--of (gas) particles.

The 3 Conditions for the Rate of Diffusion

- Speed- Diameter of gas particle- Any attractive forces

Effusion

The passing of gas particles through a tiny opening

Pressure

the force per unit area

Atmosphere

the unit we generally use to measure pressure

Standard Temperature and Pressure (STP)

exactly 1 atm and zero degrees Celsius

John Dalton

He found that for pressure of gases "the total is the sum of the parts" (which is only true if there is no chemical reaction between the gases).

Dalton's Law of Partial Pressures

- Each gas in a mixture creates pressure as if the other gases were not present.- The total pressure is the sum of the pressures created by the gases in the mixture.

Partial Pressure

the pressure each gas exerts in the mixture

Liquid

has a definite volume with a shape determined by the container

Relative Incompressibility

even at high pressures, liquids only compress a little

Viscosity

measure of the resistance of a liquid to flow

Surface Tension

force that pulls adjacent parts of a liquid's surface together, decreasing the surface area to the smallest possible size

Capillary Action

the attraction of a surface of a liquid to the surface of a solid

Meniscus

the curve in the upper surface of a standing body of liquid, produced in response to the surface of the container or another object

Vaporization

when a liquid or solid changes to a gas

Evaporation

the process during which particles escape from the surface of a non-boiling liquid and become gases

Boiling

the conversion of a liquid to a vapor--the change of a liquid to bubbles of vapor that appear throughout the liquid

Formation of solids

the KE of the particles decreases when a liquid is cooled

Freezing

the physical change of a liquid to a solid by removal of heat

Solids

Have a definite shape and definite volume

Crystalline Solids

solids with particles arranged in an orderly, geometric, repeating pattern. Such is the case for most pure minerals.

Amorphous Solids

solids with no regular, natural shape. They can flow, but do so very, very slowly (glass and plastics for example).

Melting Point

temperature at which solids change to a liquid

Metallic compounds

compounds with the highest melting points

Non-polar compounds

compounds with the lowest melting points

3 Basic Types of Crystals

- ionic- covalent- metallic

Unit Cell

the smallest arrangement of connected points that can be repeated in 3 directions to form the lattice

3 Common Unit Cells

- simple cubic- body centered cubic- face centered cubic

5 Categories of Crystalline Solids

- Atomic- Molecular- Covalent network- Ionic- Metallic

Equilibrium

dynamic condition where two opposing changes occur at equal rates in a closed system(It is achieved when the rates of the forward and reverse reactions become equal.)

Volatile Liquids

liquids that evaporate readily (because they have weak attractive forces)

Molar Enthalpy of Vaporization

the amount of heat energy required to vaporize a mole of liquid at constant pressure

Freezing Point

the temperature at which the solid and liquid are in equilibrium at 1 atmosphere

Melting

the reverse of freezing

Molar Enthalpy of Fusion

the amount of heat energy required to melt a mole of solid at its melting point

Sublimation

when a solid goes directly into a vapor, skipping the liquid step (i.e. dry ice)

Deposition

when a vapor goes directly to a solid (i.e. frost on a windshield)

Phase Diagram

a diagram used to tell us about how the system will change with changes in P and T

Triple Point

(On the phase diagram) the T and P conditions where the solid, liquid, and gas exist in equilibrium

Critical Point

(On the phase diagram) this point indicates the critical temperature and critical pressure

Critical Temperature

the temperature above which the substance cannot exist as a liquid, irrespective of pressure

Critical Pressure

the lowest pressure at which a substance can exist as a liquid at the critical temperature